Disseminated Intravascular Coagulation

Question 1

Definition

Answer 1

A disorder of the clotting cascade that can complicate a serious illness.

Question 2

What are the two forms of DIC?

Answer 2

Acute overt form (where there is bleeding and depletion of platelets and clotting factors)

Chronic non-overt form (where thromboembolism is accompanied by generalised activation of the coagulation system)

Question 3

Aetiology/Risk factors

Answer 3

Infection

Obstetric complications:
(missed miscarriage, severe pre-eclampsia, placental abruption, amniotic emboli)

Malignancy:
(acute DIC = acute promyelocytic leukaemia, chronic DIC = lung, breast and GI malignancy)

Severe trauma or surgery

Others:
(haemolytic transfusion reaction, burns, severe liver disease, aortic aneurysms, haemangiomas)

Question 4

Pathophysiology (acute)

Answer 4

· Endothelial damage and the release of granulocyte/macrophage procoagulant substances (e.g. tissue factor) lead to activation of coagulation

· This leads to explosive thrombin generation, which depletes clotting factors and platelets, whilst also activating the fibrinolytic system

· This leads to bleeding in the subcutaneous tissues, skin and mucous membranes

· Occlusion of blood vessels by fibrin in the microcirculation leads to microangiopathic haemolytic anaemia and ischaemic organ damage

Question 5

Pathophysiology (chronic)

Answer 5

· IDENTICAL process to acute DI

· Happens at a slower rate with time for compensatory responses

· The compensatory responses diminish the likelihood of bleeding but give rise to hypercoagulable states and thrombosis can occur

Question 6

Epidemiology

Answer 6

Seen in any severely ill patient

Question 7

Presenting symptoms

Answer 7

· The patients will tend to be severely unwell with symptoms of the underlying disease

· Confusion

· Dyspnoea

· Evidence of bleeding

Question 8

Signs on physical examination (general)

Answer 8

· Signs of underlying disease

· Fever

· Evidence of shock (hypotension, tachycardia)

Question 9

Signs on physical examination (acute)

Answer 9

o Petechiae, purpura, ecchymoses
o Epistaxis
o Mucosal bleeding
o Overt haemorrhage
o Signs of end organ damage
o Respiratory distress
o Oliguria due to renal failure

Question 10

Signs on physical examination (chronic)

Answer 10

o Signs of deep vein and arterial thrombosis or embolism

o Superficial venous thrombosis

Question 11

Investigations

Answer 11

Bloods (FBC):
· Low platelets
· Low Hb
· High APTT/PT
· Low fibrinogen
· High fibrin degradation products
· High D-dimers

Peripheral Blood Film:
o Schistocytes